#define _CRT_SECURE_NO_WARNINGS 1

//# include<bits/stdc++.h>
//using namespace std;
//
//typedef long long ll;
//
//int main()
//{
//    ll ans = 0, n = 0;
//    cin >> n;
//    int flg = 1;
//    for (int i = 1; i < n + 1; ++i)
//    {
//        ans += flg * i;
//        flg *= -1;
//    }
//    cout << ans;
//    return 0;
//}


# include<bits/stdc++.h>
using namespace std;

typedef long long ll;


int main()
{
    map<int, int> mp;
    int n = 0, ans = 0;
    cin >> n;
    for (int i = 0; i < n; ++i)
    {
        int tmp = 0;
        cin >> tmp;
        if (mp.count(tmp) != 0)
        {
            mp[tmp] = mp[tmp] + 1;
        }
        else
        {
            mp[tmp] = 1;
        }
    }

    for (auto it = mp.begin(); it != mp.end(); ++it)
    {
        if (it->second % 2 == 1)  ++ans;
    }
    cout << ans / 2;
    return 0;
}
